Contactor Conundrum.

[La Poste]

Greetings.

I have bought myself a Contactor to wire into the garage lights so they switch on when the electric garage door is raised.



Unfortunately it did not come with any literature and seeing as how this is the first time I have ever wired one I thought I would ask here for a bit of advice.

I am guessing that terminals 1 and 2 are for the feed signal from the door and terminals 3 and 4 are for the load which is the supply to the lights.

Is this correct?

The garage door has a small light that illuminates when the door is opened and I was thinking of wiring the feed to the Contactor in parallel with the light.

The supply to the garage lights (load) would go from a 6 Amp MCB, through the Contactor then to the lights and then back to the neutral of the board so the Contactor will be wired in parallel with the garage door light as a feed and in series with the garage lights which are the load.

Can anyone help me with this one?

Thanks very much.

 

[La Poste]

Thanks guys.

I am going to re-think this.

The unit does have a Triac.

The manual states in the specs "Triac 1A@230V"
So this is probably what controls the courtesy light as the lamp is rated at 40 Watts maximum although the manual does not say exactly what the Triac controls.

It's now a ---- up between the PIR and the limit switch, I shall have a think about this more but the main thing is not to damage the doors control unit so the Contactor wired to the courtesy light idea will have to go, it was a nice idea but too risky.

Thanks again people.

 

[Marvo]

Well good luck whichever system you decide on.

All these systems with triac operated lamps are going to be problematic when they phase out incandescent lamps. CFL's and Led lamps don't mix well with solid state switches.

 

[La Poste]

Just one more question, why do CFL's and LED's not like sold state switches?

Is this something to do with not enough current being drawn by them and thus not allowing the switch to operate properly?

 

[La Poste]

Also am I right in saying the collapsing magnetic field of the Contactor coil when switched off may induce a back EMF that could damage the Triac that is used for switching the courtesy light on/off?

A lot of questions I know but the subject's got me thinking.

 

[Marvo]

Apart from the poor quality waveform the leakage through the triac can cause the filter capacitor on the input rectifier of a CFL to charge and discharge which cause flicker even when the lamp is supposed to be off.
The capacitive load of a CFL ballast can cause the triac to stop conducting prematurely and make it multiple switch during a single cycle.
The LC filter in the CFL also causes chaos when it encounters the rapid voltage swings of the triac output waveform. Similar problems occur with the EMI filters and drivers in an LED lamp as well although LED drivers are far more complex and the latest LED lamps have been redesigned to have some of these issues addressed.

There are certain ways around these problems but you have to take the lamps on a case by case basis. As a general rule for an easy life rather just avoid using anything but filament lamp in a circuit that's switched by a triac.

 

[Engineer54]

Don't forget, you also need to be able to operate these lights from the existing switch too!!! ...lol!!!

 

[La Poste]

All the lights are already wired into a set of grid switches and work fine, it's just this little extra bit that needs sorting out.

 

[vaughant]

If you want a limit switch send me your address and I'll get you an old (but perfectly ok) one from work.
If the doors metal I'd use a proximity switch,that way you can set it a few mm off the top of the door so it never comes into contact with it like a limit does and won't wear out then but I doubt we've got any 240v switched ones,loads of 110v but your messing with transformers etc then,limit will do just fine.

 

[Knobhead]

Forget the 240V PX, I priced one for a job at work a few years back. It was enough to make your eyes water.
A limit is a cheap option, especially if you take vaughant up on his offer.

 

[La Poste]

I'll do a bit of reading this week, it's such a shame not to use the courtesy light, it really does everything I want, it has its own timer built in, it is right next to the board and it operates at 230 Volts, connecting the wires to a relay would be so easy.

It illuminates when the garage door starts to open and stays on for two minutes then switches off, perfect for what I want.

For a limit switch to do what I want it would have to be at the bottom of the door where it could be kicked or damaged, an optical device might be a safer bet you know the ones with a mirror, as soon as the door opens the beam is broken and hence the lights switch on, I could couple this with a timer and Bob's your uncle.

One other option would be to use the power to the motor as a feed to trigger a relay, as soon as the motor kicks in the lights come on, but when the motor stops the lights would switch off, maybe there is a device that can use the motor current as a trigger and then stay on for two minutes whether the motor has stopped or not.

This is entering into the realms of electronics, something I haven't studied in ages.

I just want the lights to operate when the door starts to open not when it is fully open and I want the lights to stay on for two minutes then switch off.

I shall let you know how I get on, maybe I will just give up and fit a PIR

 

[vaughant]

Mate,use a timer "on delay",it just clips on the front of the contactor,it's a mechanical device and never fails,well not in my lifetime anyway!! can then set it for 3 seconds to 30 minutes,I'll dig one out in work and even mark up where to put the wires on it for you,I'm sure we've got 240v triggered contactors there as well.
Leave me have a look tommorow when I get in on nights and we'll sort something out,you'll have it working like a dream!!

 

[vaughant]

Also you can mount the limit at the top instead,would be out of harms way then.reflectors and lasers are good but are lifed components and will eventually fail and are a lot more expensive.

 

[La Poste]

Thanks mate you're a star.

There's nothing urgent about this, it's just a conundrum that's teasing my little brain.

If I mount the switch at the top of the door the lights won't switch on until the roller reaches the top of the door.

If I mount the switch at the bottom it's likely to get damaged.

That's why I like the idea of an optical switch, the light source can be mounted out of harms way and there will only be a piece of reflective plastic attached to the bottom of the door.

 

[Knobhead]

La Poste, take vaughant up on his offer of a 2[SUP]nd[/SUP] hand limit and use my drawing. It’s the quickest and easiest way around it.

 

[La Poste]

Would a Contactor coil operate without a neutral?

Say there was no neutral in sight like behind a light switch and all you had was a live feed in and a live feed out.

Would this be enough to energise the Contactor coil or would the volt drop across the coil terminals A and B not be enough?